Solid state lighting devices are increasingly used for a wide variety of lighting applications. Solid state light sources offer advantages over traditional light sources, such as incandescent and fluorescent lamps, including long lifetime, high lumen efficacy, low operating voltage and fast modulation of lumen output, and, due to their small size have opened up new possibilities of integrating lighting with other functions. For instance, solid state solutions for providing illuminated surfaces are currently attracting attention. Illuminated surfaces may be used for general or decorative lighting, creating a desired indoor ambiance, light patterns, signage, etc.
One way of providing an illuminated surface is to use light emitting diodes (LEDs) arranged in a desired pattern on or beneath the surface to be illuminated. However, since LEDs are point light sources, very large numbers of LEDs may be required, which adds to manufacturing cost.
Another approach is to use laser light that is coupled into a light guide, e.g. an optical fiber, which is attached to or partly embedded into a surface, e.g. of a wall or a ceiling. However, known solutions using such a light guide suffer from low efficiency due to leakage of light from the light guide and absorption of light by the surface material.
Hence there is a need in the art for improvements with regard to illuminated surfaces useful e.g. for signage or decorative illumination.